downgrade to smalled exhaust piping?

[Slow_LS]

Ok so I have a huge fart can on my car. I planned on just buying an obx twinloop muffler and gettinmg 2 1/4 inch piping all the way through. But then I noticed I already have 2 1/2 all the way. Should I just keep it and weld the twinloop on or get smaller piping then weld on the twinloop. My car is an auto btw and I have no intentions od making it a track car or anything super fast like that

 

[MattLaBonte]

Id just keep the 2.5 thats what Im doing when I get the twin loop. No sense in buying new piping if you can use the existing one.

 

[sumfilipinodude]

I say keep the pipping and just weld it on. It's easier for you and I heard that 2.5 inches is an ideal diameter for an exhaust.

 

[Slow_LS]

Word I guess that will be cheaper. But I thought having that big of piping wasn't so good on a stock ls because I don't have a lot of back pressure. All I have is intake and headers

 

[jznsn2u]

I thought obx twinloops only came in 2.5 - 3 inlet sizes?

 

[Slow_LS]

oh, alrighty then i guess i will be keeping the 2.5 but is there anything i can do to get more back pressure?

 

[Rich-PMS]

oh, alrighty then i guess i will be keeping the 2.5 but is there anything i can do to get more back pressure?

Put your stock manifold back on.

You should check into a resonator also, to keep the drone/rasp to a minimum

 

[j13]

Keep the piping you have now.

 

[DC_Five_Earl]

oh, alrighty then i guess i will be keeping the 2.5 but is there anything i can do to get more back pressure?

Trust me you don't "want" more back pressure. The idea of a better exhaust system is to blow the exhaust gases out quicker,

 

[ksconekiller]

The 2.25" may ultimately be a bit better for performance, but if you aren't too concerned about that, I would keep the 2.5" since it will be cheaper for you. Like Earl said, you don't want back pressure; you want flow. Think of it this way: if you blow through a soda straw with a certain force, you feel it coming out the other end at a greater force. If you make the straw, let's say, 2" in diameter, that same blowing force doesn't come out very forcefully. It's the same thing with your exhaust, only on a less noticeable level.

Keep what you have, though.

 

[DC_Five_Earl]

The 2.25" may ultimately be a bit better for performance, but if you aren't too concerned about that, I would keep the 2.5" since it will be cheaper for you. Like Earl said, you don't want back pressure; you want flow. Think of it this way: if you blow through a soda straw with a certain force, you feel it coming out the other end at a greater force. If you make the straw, let's say, 2" in diameter, that same blowing force doesn't come out very forcefully. It's the same thing with your exhaust, only on a less noticeable level.

Keep what you have, though.

well put man:thumbs up

 

[dc2GS-R]

Well 2.5" is not optimal for your setup, but since you already have it on there...I wouldn't bother with changing it. You could go to 2.25" or 60mm (2.36"), which would be of better benefit to you. But not to the point of where I would consider it worth throwing out a perfectly good setup that you already have.

Just make sure to match the muffler to the piping. You do not want to create a bottleneck at the end of the system. If you have 2.5" piping, run a 2.5" muffler.

 

[ixcocoyxi]

so what would be better? 3" straight pipe from the cat or open cat?

 

[dc2GS-R]

so what would be better? 3" straight pipe from the cat or open cat?

Well probably open cat, although neither would be ideal on a bolt on car. The theory of "needing" backpressure stems from the fact that people realized a long time ago that going too big can hurt performance. So I suppose they jumped on the philosophy that it was backpressure that was needed to eliminate it. This theory though, is nothing but a theory...and an inaccurate one. The reason going too big screws you lies in exhaust gas velocity. Opening up the exhaust for greater flow is beneficial, but if you go too big, you create too much volume which slows exhaust gas velocity. Slower EG velocity reduces the efficiency of the engine to move air out, and also reduces scavenging effects. The idea is to, balance volume vs. velocity. Go too small and you create a restriction, go too big and you lose exhaust gas velocity and scavenging effects. Like most things automotive, balance is key.

 

[DC_Five_Earl]

so what would be better? 3" straight pipe from the cat or open cat?

Straight pipe would be great for a turbo setup :lol:

too much or too less back-pressure is bad on a n/a honda's

dude your still awake?!?! only reason i decided to post is i had a stomach ache and i had to take a mad dump. lol.:shock: